The invention relates generally to hydraulically damped rubber bearings and more particularly, to an improved hydraulically damped rubber bearing having a control device selectively permitting free movement of the end wall of the working chamber to insulate acoustic vibrations introduced in the bearing.
In DE-OS 34 47 950, a hydraulically damped rubber bearing is disclosed in which the working chamber is defined by a rubber-elastic spring member, a bearing member, a journal bearing and an end wall that is flexible in the direction of the working chamber. The end wall is provided with an elastic suspension mount that can be displaced against a stop surface in dependence upon predetermined parameters. The edges of the elastic suspension mount of the flexible end wall are fixed in a partition wall, which in turn is flexibly supported in the direction of the working chamber. When vibrations are introduced into the rubber bearing, a constant variation in the relative displacement of the end wall and the cavity results. The end wall is defined at the rear by a cavity, the base of which constitutes the stop surface. When acoustically disturbing vibrations are introduced, the rear surface of the end wall is brought into engagement with the stop face through the evacuation of the cavity. The amount of insulation achieved when acoustic vibrations are introduced into a bearing of this type is not very satisfactory.
Hence, one of the problems to which the invention is directed is to further develop a rubber bearing of the general type discussed above so that considerably improved insulation of acoustic vibrations is achieved.